Wavelength division multiplexing (WDM) is one technology that is envisioned to increase bandwidth capability and enable bidirectional communications in optical networks. In WDM networks, multiple data signals can be transmitted simultaneously between network elements (NEs) using a single fiber. Specifically, the individual signals may be assigned different transmission wavelengths so that they do not interfere or collide with each other. The path that the signal takes through the network is referred to as the lightpath. One type of WDM network, a wavelength switched optical network (WSON), seeks to switch the optical signals with fewer optical-electrical-optical (OEO) conversions along the lightpath, e.g. at the individual NEs, than existing optical networks.
One of the challenges in implementing WDM networks is the determination of the routing and wavelength assignment (RWA) for the various signals that are being transported through the network at any given time. The RWA may be implemented in a single step or in two separate steps comprising routing or path assignment and wavelength assignment (WA). When implemented separately, the path assignment may be implemented by a path computation element (PCE) while the WA may be distributed among the NEs along the path using a signaling protocol and a wavelength selection scheme.